1. Technical Field
The present invention relates to a liquid container, and more particularly to a liquid container that has, on an outer wall surface of the container body thereof, electric contacts of an information memory unit that are to be connected to a contact terminal provided on a liquid consumption apparatus.
2. Related Art
A known example of various kinds of liquid consumption apparatuses is an ink-jet recording apparatus. In a typical operation thereof, an ink-jet recording apparatus feeds ink (liquid) retained in an ink cartridge (liquid container) that is detachably attached to a cartridge attachment unit (container attachment unit) provided in the apparatus into a recording head. Then, the ink-fed recording head ejects and applies ink drops onto a recording target object such as a printing paper so as to record images, characters, or the like thereon.
A recording head of an ink-jet recording apparatus makes use of heat and/or vibration to control the ejection of ink drops. If a user attempts to execute “empty-cartridge printing” after ink retained in an ink cartridge has run out, the ink-jet recording apparatus could have a breakdown. The term “empty-cartridge printing” means, herein, an attempt to execute ink discharge operation when there is no supply of ink. In order to prevent the recording head from performing empty-cartridge printing, in a typical ink-jet recording apparatus, it is necessary to monitor the remaining amount of ink contained in the ink cartridge.
Depending on the service and working condition of an ink-jet recording apparatus, the color(s) and amount of ink consumed most heavily (in a greater amount than others) may vary from one implementation to another. For example, the colors and amount of ink consumed heavily under one service condition in which the ink-jet recording apparatus is mainly used for full-color photo printing are not the same as those consumed heavily under another service condition in which the ink-jet recording apparatus is mainly used for black-and-white text printing. In consideration of the above fact, some of the latest ink-jet recording apparatuses are configured in such a manner that the apparatus allows a part of a plurality of ink cartridges attached thereto to be replaced by another one suited for its actual service condition. In such a type of ink-jet recording apparatus, it is necessary to keep a log of “use” history, or the like, of each ink cartridge so as to identify, for example, whether an ink cartridge that gets attached to a cartridge attachment unit thereof is a new one, or a re-attached one that has been used before.
On the basis of the above-described technical needs and backgrounds, a certain type of ink cartridge has been proposed in order to provide a solution therefor. The proposed ink cartridge is provided with, firstly, information memory means (a memory chip) for storing various items of information including but not limited to the remaining amount of ink, use history, and the like, where the information memory means is provided on the container body thereof in which ink is retained, and is further provided with, secondly, on the outer wall surface of the container body thereof, electric contacts that are arranged so as to contact with a connection terminal provided at the cartridge-attachment-unit side of an ink-jet recording apparatus so as to electrically connect the information memory means to a circuit provided in the ink-jet recording apparatus.
With such an ink cartridge attached thereto, the ink-jet recording apparatus is capable of keeping an accurate log of the remaining amount of ink, which is achieved by, for example, updating the remaining amount of ink stored in the information memory means provided at the ink-cartridge side of the above-described system configuration on the basis of the amount of ink consumed during print processing or another quantitative factor. By this means, it is possible to effectively prevent the recording head from performing empty-cartridge printing. In addition, the ink-jet recording apparatus updates the use history that is memorized in the information memory means, which could be utilized, for example, to prevent any erroneous attachment of an ink cartridge.
To effectively utilize information memory means provided on an ink cartridge, however, a special technique is required in order to improve the positioning precision of the electric connection portion in the mechanical/physical contact structure constituted by the ink cartridge and the cartridge attachment unit so as to avoid any defective contact therebetween. That is, positioning precision is required to avoid any imperfect electric contact (i.e., poor electric connection state) between the electric contacts (i.e., contact points) of the information memory means provided on the ink cartridge and the connection terminal provided on the cartridge attachment unit. Imperfect electric connection could occur due to, for example, positional error and/or positional tolerance between the ink cartridge and the cartridge attachment unit. An example of a special technique for improving positioning precision is disclosed in JP-A-2003-341100.
FIG. 3 illustrates, as an example of related art, an ink cartridge 101 that is provided with the information memory means described above, and a cartridge attachment unit 111 of an ink-jet recording apparatus. The ink cartridge 101 is detachably attached to the cartridge attachment unit 111. As illustrated in FIG. 4B, the ink cartridge 101 has the shape of a low-profile rectangular parallelepiped that has a container body 102, which has an ink retainer portion inside thereof. A first positioning means 103a, a second positioning means 103b, and an ink feed port 104 are provided on the front surface 102a of the container body 102, which constitutes a first outer wall surface of the container body 102 of the ink cartridge 101.
The first positioning means 103a and the second positioning means 103b are positioning holes that are aligned in the longitudinal direction of the front surface 102a with a certain distance/space provided therebetween. The first positioning means 103a and the second positioning means 103b are configured as a pair of female joint structures into which a pair of male joint structures, specifically, a first positioning member 113a and a second positioning member 113b fit respectively. The first positioning member 113a and the second positioning member 113b (i.e., male) are provided on a first opposing surface 112, which is opposed to the front surface 102a of the container body 102 when the ink cartridge 101 is attached to the cartridge attachment unit 111, of the cartridge attachment unit 111 as illustrated in FIG. 4A. This joint structure prevents undesirable movement of the container body 102 in a direction along the front surface 102a. 
The ink feed port 104 is provided between the first positioning means 103a and the second positioning means 103b. An ink supply needle 114 illustrated in FIG. 4A, which is provided on the first opposing surface 112 of the cartridge attachment unit 111, communicates with the ink retainer portion inside via the ink feed port 104. In other words, it is inserted through the ink feed port 104 so as to reach the ink retainer portion inside.
As illustrated in FIG. 4B, the right surface 102b of the container body 102 of the ink cartridge 101, which constitutes a second outer wall surface thereof that is orthogonal to the front surface 102a thereof, has an auxiliary side surface 102c. The auxiliary side surface 102c is formed as a depression that is a step lower than the level of the right surface 102b and is in parallel with the right surface 102b. A memory substrate 105b having a plurality of electric contacts 105a on the top surface thereof is mounted on the auxiliary side surface 102c. 
The memory substrate 105b has a memory chip for storing information that is mounted on its rear surface. The electric contacts 105a provided on the top surface of the memory substrate 105b “press-contact” (i.e., get into a contact state under a pressing force) a connection/contact terminal 116 that is, as illustrated in FIG. 4A, provided on a second opposing surface 115 of the cartridge attachment unit 111, which is opposed to the right surface 102b of the container body 102 of the ink cartridge 101 when the ink cartridge 101 is attached to the cartridge attachment unit 111. By this means, the memory chip provided on the memory substrate 105b becomes electrically connected to a control circuit provided in the ink-jet recording apparatus. Through the connection established between the memory chip of the ink cartridge 101 and the control circuit provided in the ink-jet recording apparatus, it becomes possible to read/write information from/into the memory chip in response to an operation instruction given from the control circuit.
For the purpose of preventing any inadvertent detachment of the ink cartridge 101 from the cartridge attachment unit 111, as illustrated in FIG. 4B, the ink cartridge 101 has a projection 107 on the top surface 102d, which constitutes a third outer wall surface orthogonal to the front surface 102a and the right surface 102b of the container body 102 thereof.
On the other hand, as illustrated in FIG. 4A, a latch member 119 is provided on a third opposing surface 118 of the cartridge attachment unit 111 that gets opposed to the top surface 102d of the container body 102 when the ink cartridge 101 gets attached to the cartridge attachment unit 111. As illustrated in FIG. 3, the latch member 119 hooks on the rear end of the projection 107 provided on the container body 102 of the ink cartridge 101, as the ink cartridge 101 is inserted in the cartridge attachment unit 111, so as to prevent the ink cartridge 101 from being detached from the cartridge attachment unit 111.
The related-art ink cartridge 101 having a configuration described above is carefully designed so that the electric contacts 105a are provided in the close proximity of the first positioning means 103a provided on the front surface 102a of the container body 102. With such a configuration, positioning precision of the electric contacts 105a with respect to the connection terminal 116 is heightened to some degree, which reduces the occurrence of imperfect electric connection between the connection terminal 116 and electric contacts 105a. 
Disadvantageously, however, in the configuration of the related-art ink cartridge 101 described above, the auxiliary side surface 102c on which the electric contacts 105a are provided does not constitute the same surface as the top surface 102d on which the projection is provided. That is, the auxiliary side surface 102c is orthogonal to the top surface 102d. Therefore, as illustrated in FIG. 3, the position of the projection 107 is “offset” by a distance L in a planar direction of the memory substrate 105b. As a result of such an offset, assuming that the pressing/hooking force of the latch member 119 applied to the projection 107 is denoted as F, a moment M, which is mathematically expressed as F times L, is generated. The moment M is a force that rotationally displaces the container body 102 attached to the cartridge attachment unit 111 along the planar direction of the memory substrate 105b around the male-female joint position defined by the first positioning member 113a and the first positioning means 103a. Since the moment M(=F×L) works as a force that causes the position of the electric contacts 105a, which are supposed to contact the connection terminal 116, to be shifted in the planar direction of the memory substrate 105b, the contact area and/or the contact pressure between the electric contacts 105a and the connection terminal 116 become unreliable, which could result in a poor mechanical/physical contact, meaning a bad electric connection therebetween.
In order to address, for example, the above-identified problems without any limitation thereto, as an advantage of some aspects of the invention, the invention provides a liquid container that causes the electric contacts of an information memory unit that is provided on the liquid container to mechanically contact the connection/contact terminal of a container attachment unit/mechanism with a stable contact pressure in a reliable manner when the liquid container is attached to the container attachment unit.